Normal Labour

Normal LabourShehr Bano08-180Batch-K Final YearOutlineDefinitionsCriteria of normal labourComponents of normal labourOverview of anatomy of female pelvis & fetal skullOnset of LabourStages of LabourIntrapartum monitoringManagment

DefinitionsLabour:Event that takes place in the uterus and the birth canal to expel the viable fetus through the vagina

Delivery:The expulsion of a viable fetus out of the uterus

Normal Labour (eutocia):Labour is considered normal when mature fetus presenting by vertex delivers by natural effortsCriteria for normal labour Labour is considered to be Normal when it meets the following criteria:

Spontaneous expulsionSingle ,Full term i.e mature fetus (37 completed weeks 42 weeks) Through vaginaPresented by vertexWithin a reasonable time (not less then 3 hours or more then 18 hours)Without aid (episiotomy or oxytocin)Without complications to the mother or the fetus.Components of Normal labourComponents of normal labour are denoted by 3 Ps as the Passage , Passenger & Power.

Passage refers to the birth canal as a whole formed by soft tissues covering the bony pelvis through which the fetus is expelled during labour. This includes the pelvic inlet , pelvic cavity and the pelvic outlet.

Passenger refers to the fetus. This includes the fetuss attitude, lie, presentation and its position

Power denotes the force exerted during the labour. This is of two types Primary force: actions of the uterine musclesSecondary force: the involuntary contraction of muscles of diaphragm and anterior abdominal wall (the bearing down effort)Anatomy of Female pelvis

A. View from above, showing inlet and anteroposterior (11 cm) and transverse diameters (13.5 cm) and surrounded by drawings of the four main types of female pelvis.

B. View from below, showing outlet and anteroposterior (13.5cm) and transverse diameters(11 cm)The Fetus Lie: Relation of long axis of fetus to long axis of uterus. Normally its Longitudinal lie

Presentation:part of fetus occupying lower segment of uterus lying just above the internal os. In normal labour presntation should be vertex

Attitude: relation of fetal head and limbs to its trunk. Normally it should be flexed.

Position: positon of fetus in relation to pelvis of mother described in terms of a certain point on the presenting part called the denominator. Four possible positions for each presentation in accordance to the pelvis. These are left and right anterior and left and right posterior

Fetal SkullNormal Dimensions:OvoidLongitudinal diameter(suboccipito-bregmatic): 9.5 cm measured from subboccipital region to center of anterior fontanalle(the bregma)

Moulding:During a head first birth, pressure on the head caused by the tight birth canal may "mold" the head into an oblong rather than round shape.

The gaps or spaces (fontanalles)allow the baby's head to change shape. Depending on the amount and length of pressure, the skull bones may even overlap.

Fetal skull moulding

Onset of labourThe onset of labour is defined as the time of onset of regular, painful uterine contractions, which produce progressive effacement and dilatation of the cervix.

The clinical signs of the onset of labour

1. The onset of regular, painful contractions that produce progressive cervical dilatation.

2. The exhibition of a vaginal show - the passage of blood stained mucus.

3. Rupture of the fetal membranes - may occur at the time of onset of contractions or it may be delayed until the delivery of the fetus.

Stages of Labour

1st Stage

2nd Stage

3rd Stage: The Placental stage

Mechanism Of LabourRefers to series of changes in position and attitude that fetus undergoes during its passage through the birth canal

Engagement of the head(passage of widest part of fetal head through the inlet) normally occurs before the onset of labour in the primigravid woman but may not occur until labour is well established in a multipara.

Only 2/5th of the head will be palpable per abdomen

1. Descent of the head provides a measure of the progress of labour

Descent occurs throughout labour

2. Flexion of the head occurs as it descends and meets the pelvic floor, bringing the chin into contact with the fetal thorax.

Flexion produces a smaller diameter of presentation (suboccipitobregmatic diameter)

3. Internal rotation: The head rotates as it reaches pelvic floor and the occiput normally rotates anteriorly from the lateral position towards the pubic symphysis

4. Extension: The acutely flexed head descends to distend the pelvic floor and the vulva, and the base of the occiput comes into contact with the inferior rami of the pubis.

The head now extends until it is delivered. Maximal distension of the perineum and introitus accompanies the final expulsion of the head, a process that is known as crowning.

5. Restitution: Following delivery of the head, it rotates back to be in line with its normal relationship to the fetal shoulders

6. External rotation: When the shoulders reach the pelvic floor, they rotate into the anteroposterior diameter of the pelvis. This is accompanied by rotation of the fetal head so that the face looks laterally at the maternal thigh.

7. Delivery of the shoulders: The anterior shoulder is delivered first by traction posteriorly on the fetal head so that the shoulder emerges under the pubic arch.

The posterior shoulder is delivered by lifting the head anteriorly over the perineum. This is followed by rapid delivery of the remainder of the trunk and the lower limbs

Mechanism of labourIntra partum MonitoringWhat to monitor? Mother Temperature Pulse rate Blood pressure Urine

Fetus Auscultation Fetal CTG Fetal ECG Scalp stimulation test Acid-Base balance Others

Partogram

Maternal MonitoringTemperature Normal Temperature 36.2-37.2 Frequency Every 4 hours Pyrexia; Causes Infection Maternal exhaustion: Dehydration cause pyrexia

Pulse Rate Normal Range 70-100 beats per min Frequency Hourly

Blood Pressure Normal Range 100/60 mm Hg to 140/90 mm Hg Frequency hourly

Urine Items Volume Protein Ketones Frequency Every 2 hours

Fetal MonitoringAuscultation Fetal CTG Fetal ECG Acid-Base balance Scalp stimulation test Others Vibroacoustic stimulation Fetal oxygen saturation

Auscultation The heart rate should be recorded every 15 minutes in the first stage and after each contraction in the second stage, using a Pinard fetal stethoscope Cardiotocography is not required when the labour is classified as low risk. However, there are specific indications for electronic fetal monitoring.

Indications for continuous electronic fetal monitoring Maternal Previous caesarian section Pre-eclampsia Post-term pregnancy Premature rupture of the membranes Induced labour Diabetes Antepartum haemorrhage Other maternal medical diseases

Fetal Fetal growth restriction Prematurity Oligohydramnios Multiple pregnancy Meconium-stained liquor Breech presentation

Partogram Partogram is a graphical record of key data (maternal and fetal) during labour entered against time on a single sheet of paper

Components Fetal Parameters: FHR Status of membranes or Amniotic Fluid Moulding Caput

Progress of Labor: Cervical dilatation Station of head Uterine contractions: Frequency & Duration

Oxytocin: Concentration / L Infusion rate

Any other medicine & IV fluid

Components of Partogram (Cont.)Maternal Parameters:

Vital data: Pulse BP Temperature

Urine: Output Acetone Protein / Glucose

Management Of Normal LabourGeneral principles of the management of the first stage of labour :

Observation and intervention if the labour becomes abnormal by partogram .

Pain relief during labour and emotional support for the mother ( Narcotic agents , inhalational analgesia and regional analgesia )

Adequate hydration throughout labour. Fetal monitoring in labour

Fetal cardiotocography Basal heart rate Transitory changes The fetal electrocardiogram Fetal acid-base changes Scalp blood sampling

Management of the second stage Delivery of the head Controlled descent: mother should be adviced to take rapid shallow breaths once the head has been crowned

Minimizing perineal damage.

Clamping the cord: no need of immediate clamping as about 80 ml blood may be transferred to baby until the cord pulsations cease

Evaluation of Apgar score.

Vit-K first dose

Evaluation of the Apgar score

Management of the third stage Recognition of placental separation: signs: lengthening of cord small gush of blood that stops quickly rising fundus of uterus to umbilicusFundus becomes hard and globular

Controlled cord tractionRoutine use of oxytocic agents with crowning of the head: synthetic oxytocin or oxytocin + ergometrin (if mother is not HTN) following delivery of shoulder. Causes uterus to contract after delivery of baby.

Assisted delivery of the placenta with cord traction: cord clamping after 1-2 mins after delivery of baby close to vulva to notice lengthening. When contraction is felt, fundus should be elevated with palm by the attendant with steady traction applied to the cord at the same time ,so that placenta separates and delivers gently.

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